PolyHIPEs from Methyl methacrylate: Hierarchically structured microcellular polymers with exceptional mechanical properties

Highly porous monoliths with excellent mechanical properties and porosity of up to 90% were prepared by the polymerisation of high internal phase emulsions (HIPE) containing methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA). Materials with open cellular morphology and cavity diameters between 0.6 and 4.5 μm are obtained using a homogenizer and between 0.8 and 25 μm using a standard overhead stirrer. Samples with 80% pore volume have E-moduli up to 180 MPa, while 75% porous samples exhibit E-moduli up to 211 MPa. A dependence of mechanical properties on cavity size distribution is identified, where a more hierarchically developed porous structure results in significantly better mechanical properties.